Cryogenic systems may contain circuits that require voltage and current to be transferred from one temperature domain to a lower temperature domain. For example, the electronic system may include a first temperature domain at 300 Kelvin (K) and a second temperature domain at 4K. There are other temperature domains that may be used as the second temperature domain, such as 77K. Copper conductors are used to transfer the voltage and current between components in the temperature domains. The voltage and current on the copper conductors conduct heat into the low temperature domain using two ways: a first way is thermal conduction and the other way is electrical heating.
Heat flow to the second temperature domain in a cryogenic digital system is a concern. To pull the heat out at a cryogenic temperature domain, such as by a cooling subsystem, there is a large efficiency factor that affects the amount of energy at room temperature needed. For signaling between components in two temperature domains, the signaling system is noise limited by the input devices of a complementary metal-oxide-semiconductor (CMOS) input amplifier. This noise may be thermal noise and flicker noise caused by the CMOS input amplifier operating in a higher temperature domain than the transmitter.